As celebrities go, they don't get much bigger than Robert Redford, Oscar-winning filmmaker, actor and founder of the Sundance Film Festival.

But then there's Oprah Winfrey, who's in a class by herself. So what did Redford think when the queen of daytime talk came to his festival for the first time this year?

The 56-year-old talk show host came to Sundance to attend a party for her new OWN network, which has been busy scouting for product at the festival. Oprah's team snapped up the new documentary about Chaz Bono, Cher's son (who was born Chastity Bono) and they've been eyeing other films.

Redford is a huge advocate of documentaries, so in his book O is a-O-kay (we couldn't resist!). He told CNN in an exclusive interview that he applauds Oprah's decision to promote documentary filmmaking and welcomes her to Sundance.

It looks like tiny Park City, Utah apparently is big enough for two giant stars.